<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      #root {
        display: flex;
        justify-content: center;
      }
      #panel {
        width: 300px;
        height: 300px;
        background: #000;
        position: relative;
      }
      #next {
        position: relative;
        width: 120px;
        height: 120px;
      }
    </style>
  </head>
  <body>
    <div id="root">
      <div id="panel"></div>
      <div id="tip">
        <div id="next"></div>
      </div>
      <div>
        <button id="start">开始</button>
        <button id="pause">暂停</button>
        <button id="left">left</button>
        <button id="right">right</button>
        <button id="down">down</button>
        <button id="rotate">rotate</button>
      </div>
    </div>
  </body>
</html>
